<?php

/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Http
 * @subpackage Client_Adapter
 * @version    $Id$
 * @copyright  Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */

/**
 * @see Zend_Uri_Http
 */
require_once 'Zend/Uri/Http.php';
/**
 * @see Zend_Http_Client
 */
require_once 'Zend/Http/Client.php';
/**
 * @see Zend_Http_Client_Adapter_Socket
 */
require_once 'Zend/Http/Client/Adapter/Socket.php';

/**
 * HTTP Proxy-supporting Zend_Http_Client adapter class, based on the default
 * socket based adapter.
 *
 * Should be used if proxy HTTP access is required. If no proxy is set, will
 * fall back to Zend_Http_Client_Adapter_Socket behavior. Just like the
 * default Socket adapter, this adapter does not require any special extensions
 * installed.
 *
 * @category   Zend
 * @package    Zend_Http
 * @subpackage Client_Adapter
 * @copyright  Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Http_Client_Adapter_Proxy extends Zend_Http_Client_Adapter_Socket
{
    /**
     * Parameters array
     *
     * @var array
     */
    protected $config = [
        'ssltransport'  => 'ssl',
        'sslcert'       => null,
        'sslpassphrase' => null,
        'sslusecontext' => false,
        'proxy_host'    => '',
        'proxy_port'    => 8080,
        'proxy_user'    => '',
        'proxy_pass'    => '',
        'proxy_auth'    => Zend_Http_Client::AUTH_BASIC,
        'persistent'    => false,
    ];

    /**
     * Whether HTTPS CONNECT was already negotiated with the proxy or not
     *
     * @var boolean
     */
    protected $negotiated = false;

    /**
     * Stores the last CONNECT handshake request
     *
     * @var string
     */
    protected $connectHandshakeRequest;

    /**
     * Connect to the remote server
     *
     * Will try to connect to the proxy server. If no proxy was set, will
     * fall back to the target server (behave like regular Socket adapter)
     *
     * @param string  $host
     * @param int     $port
     * @param boolean $secure
     */
    public function connect($host, $port = 80, $secure = false)
    {
        // If no proxy is set, fall back to Socket adapter
        if (!$this->config['proxy_host']) {
            return parent::connect($host, $port, $secure);
        }

        /* Url might require stream context even if proxy connection doesn't */
        if ($secure) {
            $this->config['sslusecontext'] = true;
        }

        // Connect (a non-secure connection) to the proxy server
        return parent::connect(
            $this->config['proxy_host'],
            $this->config['proxy_port'],
            false
        );
    }

    /**
     * Send request to the proxy server
     *
     * @param string        $method
     * @param Zend_Uri_Http $uri
     * @param string        $http_ver
     * @param array         $headers
     * @param string        $body
     * @return string Request as string
     * @throws Zend_Http_Client_Adapter_Exception
     */
    public function write(
        $method,
        $uri,
        $http_ver = '1.1',
        $headers = [],
        $body = ''
    ) {
        // If no proxy is set, fall back to default Socket adapter
        if (!$this->config['proxy_host']) {
            return parent::write($method, $uri, $http_ver, $headers, $body);
        }

        // Make sure we're properly connected
        if (!$this->socket) {
            require_once 'Zend/Http/Client/Adapter/Exception.php';
            throw new Zend_Http_Client_Adapter_Exception(
                'Trying to write but we are not connected'
            );
        }

        $host = $this->config['proxy_host'];
        $port = $this->config['proxy_port'];

        if ($this->connected_to[0] != "tcp://$host"
            || $this->connected_to[1] != $port
        ) {
            require_once 'Zend/Http/Client/Adapter/Exception.php';
            throw new Zend_Http_Client_Adapter_Exception(
                'Trying to write but we are connected to the wrong proxy server'
            );
        }

        // Add Proxy-Authorization header
        if ($this->config['proxy_user']) {
            // Check to see if one already exists
            $hasProxyAuthHeader = false;
            foreach ($headers as $k => $v) {
                if ((string) $k == 'proxy-authorization'
                    || preg_match("/^proxy-authorization:/i", $v)
                ) {
                    $hasProxyAuthHeader = true;
                    break;
                }
            }
            if (!$hasProxyAuthHeader) {
                $headers[] = 'Proxy-authorization: '
                    . Zend_Http_Client::encodeAuthHeader(
                        $this->config['proxy_user'],
                        $this->config['proxy_pass'],
                        $this->config['proxy_auth']
                    );
            }
        }

        // if we are proxying HTTPS, preform CONNECT handshake with the proxy
        if ($uri->getScheme() == 'https' && (!$this->negotiated)) {
            $this->connectHandshake(
                $uri->getHost(),
                $uri->getPort(),
                $http_ver,
                $headers
            );
            $this->negotiated = true;
        }

        // Save request method for later
        $this->method = $method;

        // Build request headers
        if ($this->negotiated) {
            $path = $uri->getPath();
            if ($uri->getQuery()) {
                $path .= '?' . $uri->getQuery();
            }
            $request = "$method $path HTTP/$http_ver\r\n";
        } else {
            $request = "$method $uri HTTP/$http_ver\r\n";
        }

        // Add all headers to the request string
        foreach ($headers as $k => $v) {
            if (is_string($k)) {
                $v = "$k: $v";
            }
            $request .= "$v\r\n";
        }

        if (is_resource($body)) {
            $request .= "\r\n";
        } else {
            // Add the request body
            $request .= "\r\n" . $body;
        }

        // Send the request
        if (!@fwrite($this->socket, $request)) {
            require_once 'Zend/Http/Client/Adapter/Exception.php';
            throw new Zend_Http_Client_Adapter_Exception(
                'Error writing request to proxy server'
            );
        }

        if (is_resource($body)) {
            if (stream_copy_to_stream($body, $this->socket) == 0) {
                require_once 'Zend/Http/Client/Adapter/Exception.php';
                throw new Zend_Http_Client_Adapter_Exception(
                    'Error writing request to server'
                );
            }
        }

        return $request;
    }

    /**
     * Preform handshaking with HTTPS proxy using CONNECT method
     *
     * @param string  $host
     * @param integer $port
     * @param string  $http_ver
     * @param array   $headers
     * @return void
     * @throws Zend_Http_Client_Adapter_Exception
     */
    protected function connectHandshake(
        $host,
        $port = 443,
        $http_ver = '1.1',
        array &$headers = []
    ) {
        $request = "CONNECT $host:$port HTTP/$http_ver\r\n" .
                   "Host: " . $host . "\r\n";

        // Process provided headers, including important ones to CONNECT request
        foreach ($headers as $k => $v) {
            switch (strtolower(substr($v, 0, strpos($v, ':')))) {
                case 'proxy-authorization':
                    // break intentionally omitted

                case 'user-agent':
                    $request .= $v . "\r\n";
                    break;

                default:
                    break;
            }
        }
        $request .= "\r\n";

        // @see ZF-3189
        $this->connectHandshakeRequest = $request;

        // Send the request
        if (!@fwrite($this->socket, $request)) {
            require_once 'Zend/Http/Client/Adapter/Exception.php';
            throw new Zend_Http_Client_Adapter_Exception(
                'Error writing request to proxy server'
            );
        }

        // Read response headers only
        $response = '';
        $gotStatus = false;
        while ($line = @fgets($this->socket)) {
            $gotStatus = $gotStatus || (strpos($line, 'HTTP') !== false);
            if ($gotStatus) {
                $response .= $line;
                if (!chop($line)) {
                    break;
                }
            }
        }

        // Check that the response from the proxy is 200
        if (Zend_Http_Response::extractCode($response) != 200) {
            require_once 'Zend/Http/Client/Adapter/Exception.php';
            throw new Zend_Http_Client_Adapter_Exception(
                'Unable to connect to HTTPS proxy. Server response: ' . $response
            );
        }

        // If all is good, switch socket to secure mode. We have to fall back
        // through the different modes
        $modes = [
            STREAM_CRYPTO_METHOD_TLS_CLIENT,
            STREAM_CRYPTO_METHOD_SSLv3_CLIENT,
            STREAM_CRYPTO_METHOD_SSLv23_CLIENT,
            STREAM_CRYPTO_METHOD_SSLv2_CLIENT
        ];

        $success = false;
        foreach ($modes as $mode) {
            $success = stream_socket_enable_crypto($this->socket, true, $mode);
            if ($success) {
                break;
            }
        }

        if (!$success) {
            require_once 'Zend/Http/Client/Adapter/Exception.php';
            throw new Zend_Http_Client_Adapter_Exception(
                'Unable to connect to HTTPS server through proxy: could not '
                . 'negotiate secure connection.'
            );
        }
    }

    /**
     * Close the connection to the server
     *
     */
    public function close()
    {
        parent::close();
        $this->negotiated = false;
    }

    /**
     * Destructor: make sure the socket is disconnected
     *
     */
    public function __destruct()
    {
        if ($this->socket) {
            $this->close();
        }
    }
}
